I have a 684 credit score on a 90% ltv mtg. I am currently paying 21% interest in TN. Could I get a refi now

I am curently purchasing my first home. I have a mid credit score of 534. (which is bad) And my rate is under 8%. I am working with Quicken Loans to purchase the home. If I can buy a house on a salary of 23000.00 a year you should be able to refinance for a lower rate.